1. Field of the Invention
The present invention relates to an optical module, in particular, the invention relates to a transmitting optical module applied in the optical communication system.
2. Related Prior Art
The transmitting optical module generally installs a semiconductor laser diode that converts an electrical signal into a corresponding optical signal. In particular, a small-sized transmitting module typically provides a CAN-type package to install the laser diode (hereafter denoted as LD). Various prior patents have disclosed such optical module with the CAN-type package.
For instance, an U.S. Pat. No. 7,026,655 has disclosed an optical module with an LD and a transistor to drive the LD both of which are mounted on the base provided in a stem that constitutes the CAN-type package. This optical module installs the LD and the driving transistor within the package, which makes it possible to mount the transistor immediate to the LD and to lower the parasitic impedance between the LD and the transistor to suppress the signal degradation.
Another U.S. Pat. No. 7,218,657, has disclosed a type of an optical module with the CAN-type package in which the stem installs the LD and the temperature sensor thereon. This optical module, because of the LD and the sensor on the stem, has made it possible to control the driving current for the LD precisely without being affected from an ambient temperature. In these modules, the stem has provided a block extruding from the primary surface thereof, and the block has mounted the LD thereon.
Still another U.S. Pat. No. 7,037,001, has disclosed a type of an optical transmitting module that provides auxiliary members to extend the lead pins behind the block to a front side of the block. The auxiliary members are fixed to the tip of the lead pins in one end wire-bonded to the device on the block in the other end. The auxiliary member detours the block so as not to come in contact with the block.
Small-sized optical module has been continuously requested. The module with the CAN-type package provides the block to mount the optical device, and this block provides a surface as the mounting area for the device only in one side thereof facing the center portion of the stem. That is, the conventional block has a D-shape cross section with a flat side surface facing the center portion to mount the device thereon. Accordingly, the conventional module is hard to mount electronic devices with large die area, or to miniaturize the package.
The block with a rectangular cross section may provide mounting areas in both side surfaces, one of which faces the center portion of the stem, while, the other faces an outside of the module. However, devices mounted on both side surfaces are hard to be electrically connected with each other. To provide an auxiliary member such as those disclosed in the U.S. Pat. No. 7,037,001 may be a solution for this subject, but it may cause to degrade the reliability in mechanical and electrical to apply the auxiliary member.
The present invention is to provide a new solution for the above subjects, that is, to enhance the flexibility of the device mounting and to enable the electrical connection between devices mounted on respective sides of the block.